trace fossil

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A fossil consisting of an imprint or mark left by an organism, such as a footprint or a tunnel, in contrast to a fossil of an organism's remains.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A type of fossil reflecting the reworking of sediments and hard substrates by organisms, rather than the physical remains of the organism itself. This includes structures such as burrows, trails, impressions, coprolites and borings.